1. Field of the Invention
This invention relates to a simple hardware module that may be coupled between a source of video signals and a video monitor, for modifying the gray scale of selected portions of a two-dimensional video image.
2. Discussion of the Prior Art
There are sophisticated computer programs that produce graphics that are characterized by representations of plane or curved surfaces in the apparent spatial relations as they would appear to the eye. That is, the image graphics give the appearance of depth in three dimensions by applying the principles of artistic perspective. Such programs typically require massive amounts of memory far beyond the capabilities of modest-sized personal computers. One such program, AutoShade.RTM., provided by Autodesk of Sausalito, Calif., requires about 350 kb of RAM.
Another such system is taught by U.S. Pat. No. 4,410,908, issued 10/18/83 to Belmares-Sarabia et al. for a Luminance Signal Generator for a Color Film Scanner. Another teaching of interest is U.S. Pat. No. 4,590,465, issued 05/20/86 to Henry Fuchs for a Graphics Display System Using Logic Enhanced Pixel Memory Cells. A third system is exemplified by U.S. Pat. No. 4,853,970, issued 08/01/89 to David and Cynthia Ott for an Apparatus for Processing Digitized Images. All of those references require complicated circuitry and internal programming steps that, while suitable for studio-type processing, are far too complex for a personal computer of limited capacity.
In applications such as video games, computer-aided design applications and computer simulations, the images are presented as simple two-dimensional displays because it would be uneconomical program-wise and cost-wise, to attempt a more aesthetic presentation.
It is the object of this invention to provide a simple means and method for inexpensively, in terms of both memory and disk space as well as in terms of money, imparting a simulated depth of field to displayed two-dimensional video images as provided by a source of video signals such as a graphics computer or a VCR.